Date of Degree

9-2020

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor

Joel Sneed

Committee Members

Joan Borod

Yvette Caro

Valentina Nikulina

Justin Storbeck

Subject Categories

Cognitive Psychology

Keywords

Computerized cognitive training, cognitive symptoms of depression, young adults, non-specific factors, active control condition

Abstract

Background: Depression is associated with a broad range of cognitive symptoms, including reduced attention, verbal learning and memory, executive functioning (EF), and processing speed (PS). Computerized cognitive training (CCT) has been shown to ameliorate the cognitive symptoms of depression. Younger adults, in particular, are understood to benefit more from CCT than older adults due to their greater capacity for neuroplasticity. However, several issues remain unclear about the effectiveness of CCT: (1) whether the benefits of CCT are driven by the specific content or by non-specific factors, such as engagement, motivation, novelty, and expectancy, which have been inadequately controlled in prior studies; (2) whether the benefits of CCT extend past the domains directly trained (i.e., far transfer); and (3) whether CCT response is impacted by socio-demographic and clinical variables. To address these issues, we devised an 8-week, double-blind randomized trial that compared the cognitive effects of PS and EF-based CCT (treatment group) versus verbal-based CCT (active control) in young adults with elevated depressive symptoms. We hypothesize PS/EF-based CCT will result in differentially larger improvements in near (PS and EF) and far transfer (attention and verbal learning and memory) than in the active control group. We also hypothesize that race, concurrent treatment and depression severity predicts CCT response.

Methods: Forty six young adults (18-29 years old) with at least mild depressive symptoms (Hamilton Depression Rating Scale ≥ 10) were randomized to one of two CCT programs. Participants completed a baseline neuropsychological evaluation, downloaded an app with their respective training program, and were instructed to train for a minimum of 15 minutes a day, 5 days a week, for 8 weeks. Both groups had an equal and limited amount of time with research personal, thereby controlling for social engagement. All modules scaled in difficulty and provided motivational reinforcement upon performance, thereby controlling for motivation, novelty, and expectancy. After 8 weeks, participants returned for a neuropsychological re-evaluation. The primary outcome variables were change scores (from baseline to week 8) of each cognitive test administered, as well as for mood and daily functioning. Race, concurrent treatment, and depressive severity were explored as potential predictors of CCT response.

Results: The PS/EF group demonstrated significantly greater gains on select measures of PS and EF than the active control group. Comparable improvement was observed between groups on farther measures of cognition, as well as in mood and daily functioning. Both groups reported comparable levels of engagement. Differential response to CCT was noted between Whites and Asians, whereas concurrent treatment and depressive severity were largely unremarkable, yet with a few exceptions.

Conclusion: PS/EF-based CCT was more effective on tasks of near transfer, but comparably effective as the active control on measures of far transfer. This suggests the mechanism of action in CCT is likely not driven by the specific training content, but on the factors common to both training conditions. The role of non-specific factors cannot be ruled out, given comparable levels of engagement and exposure to a novel and challenging activity. The possibility that CCT is effective insofar as it upregulates brain derived neurotrophic factor is discussed. Future research is recommended to better elucidate the relationships among CCT, cognitive functioning, and demographic and clinical variables in young adults with depression.

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